Face Missions

Face Missions are referred to as "Favors" in the game. They also include the Random Events and Dating Missions, none of which may be replayed (so when you find one, complete them and then save the game ... or you will not get the Chief Inspector achievement or trophy).

Some Face missions unlock new main story missions, while others are unlocked after other mission types (Cop, Main, etc.) are completed. The rule of thumb is to wipe the map of all objective markers for 100%.